As mobile phones and other hand-held devices incorporate increasingly more powerful processors, it has become possible to add previously impractical applications to these devices, like streaming video and graphic-intensive games. Users, when presented with these options, take advantage of them. In situations where the video information is delivered from a remote source over a network, this may result in a significant increase in network bandwidth utilization. Since network bandwidth typically is not a free resource, the increased utilization of network bandwidth by, for example, video information may have negative consequences. These consequences may be, for example, decreased quality of other services supported by a network, if the increased bandwidth utilization overwhelms network resources; and the need to augment the physical infrastructure of a network to accommodate the increased bandwidth utilization.
Even if the video is sourced from the mobile or hand-held devices themselves (e.g., from a resident graphic-intensive game) the graphics demands presented by such applications may significantly degrade the ability of these devices to multitask. Heretofore, true multitasking capability has been the province of much larger devices like notebook and desktop computers. Mobile and other hand-held devices have typically used RISC-class (“Reduced Instruction Set Computer”—a typical architecture selected for microprocessors incorporated in mobile devices) processors that have a significantly decreased multitasking capability when compared to desktop-class processors. Only at the present time have fabrication advances resulted in the ability to manufacture practical multi-core devices for incorporation in hand-held or mobile devices. Notwithstanding that such mobile multi-core processors are becoming available, these devices remain battery-powered and, as such, have a limited supply of power for supporting multi-tasking. Accordingly, those skilled in the art seek ways to provide high-quality video with simultaneous multitasking ability in such a way so that current battery performance is sufficient to provide acceptable time durations between recharging.
One of the reasons that video is perceived as a processing- and power-hungry application is that it has been felt necessary up until recently to provide full resolution video across the full extent of a display device. Full-resolution video has been perceived as necessary because those skilled in the art until recently did not appreciate the properties of human vision. For example, when a human views an image, typically only a small portion of the image is viewed at high resolution. Areas around a so-called “gaze fixation point” (a part of an image or video that a user is focused on) are seen with decreasing sharpness in dependence on their respective distance from the gaze fixation point. In addition, as a human moves his or her “gaze fixation point” sufficiently quickly to constitute saccadic eye movement from one portion of an image or video to another portion of an image or video, the sharpness of vision falls off markedly and the user is effectively blind for a short period of time. This is in contrast to smooth eye movement where significant visual acuity may be maintained. Accordingly, when it is known that the display environment is directed to a single user, it is only necessary to show an image with a high degree of resolution in an area coincident with a user's gaze fixation point. Reproducing the image in areas around the periphery and beyond of the gaze fixation point is effectively wasteful, since as long as the user is not looking directly at these regions the extra resolution (any resolution above the limited resolution of human peripheral vision) is not used. In addition, updating imagery while a viewer is manifesting quick (saccadic) eye movement is wasteful since during such periods of eye movement changes in image content will not be appreciated by a viewer.
In a multi-viewer environment like television where multiple viewers may be watching, and where each of the viewers may be looking at different portions of the video, this selective-resolution feature of human vision may be used to reduce bandwidth requirements, but with more difficulty. For example in such a situation, one viewer may be looking directly at a region of an image or video that is in the peripheral field of view of another viewer. Thus, if the portion of an image or video that coincided with the peripheral field of view of another was produced at a significantly lower resolution (a resolution below that of the effective resolution of human vision at the gaze fixation point) then a viewer whose gaze fixation point coincided with the reduced-resolution region would find this mode of reproduction totally unacceptable. Therefore one would need to have as many areas of high resolution as there are viewers. However, in many cases viewers would be looking at the same area of the screen.
Some progress has been made in incorporating these facts about human vision in practical systems. However, those skilled in the art seek further improvements. In particular, those skilled in the art seek improvements that can be incorporated in distributed systems.